Heat exchanger tube weaving apparatus and method

ABSTRACT

A weaving apparatus used to separate the tubes of a heat exchanger so that spacers that hold the tubes apart can be inserted between the tubes to increase thermal efficiency. The weaving apparatus includes a frame assembly and a weaving mechanism contained within the frame assembly. The weaving mechanism includes an alignment plate to align the tubes and separation plates to separate the tubes after they have been aligned. The weaving apparatus thus automates the step of separating the tubes of the heat exchanger so that the spacer can ready inserted between the tubes.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates generally to heat exchangers, and moreparticularly, to a weaving apparatus and method used to separate thetubes of a heat exchanger so that spacers that hold the tubes apart canbe inserted between the tubes to increase thermal efficiency.

2. Description of the Related Art

Heat exchangers are devices used to quickly and efficiently either coolor heat a gas or liquid (hereafter generically referred to as a“fluid”). A typical heat exchanger includes a pair of header pipes and aplurality of heat exchanger tubes arranged substantially in parallel andadjacent to one another between the header pipes. During operation,fluid is introduced into one of the header tubes. The fluid then travelsthrough the plurality of heat exchange tubes and then passes through thesecond header pipe to exit the heat exchanger. With a heat exchangerused to cool a hot fluid, the tubes are maintained in a coolingenvironment. As the hot fluid passes through the heat exchanger, it iscooled by heat transfer through the tubes. With heat exchangers thatheat a fluid, the tubes are maintained in a hot environment and thefluid is warmed by heat transfer through the tubes. In general, thelarger the heat transfer surface area of the exchanger, the moreefficient the device. For this reason, heat exchangers tend to have alarge number of tubes.

The heat exchangers offered by FAFCO Incorporated, Redwood City, Calif.,assignee of the present application, have heat exchange tubes made of athermoplastic material heat welded to the header tubes. When thesedevices are initially manufactured, the heat exchange tubes aretack-welded together before being welded to the header tubes. Thisarrangement, however, is less than ideal. The tack-welds between thetubes reduce the overall performance of the heat exchanger because theyprevent the free flow of the external environment (typically either agas or a liquid) from circulating around the tubes. To remedy thisproblem, the tack-welds between the pipes are broken and spacers areinserted between the tubes forming multiple rows of separate tubes. Thespacers physically separate the tubes from one another increasing thecirculation around the tubes. For more information on FAFCO's heatexchangers, see U.S. patent application Ser. No. 09/220,639 entitled“Heat Exchanger Having Heat Exchange Tubes with Angled Heat-ExchangePerformance Improving Indentations, filed Dec. 24, 1998 and U.S. patentapplication Ser. No. 09/094,187, now U.S. Pat. No. 6,038,768 entitled“Method and Apparatus for Coupling Panel Boards and Tubing to a HeaderPipe” filed Jun. 9, 1998, both assigned to the assignee of the presentinvention and incorporated by reference herein.

The problem with the aforementioned heat exchangers is that the steps ofbreaking the tack-welds and inserting the spacers are performedmanually. Given the large number of tubes per heat exchange unit andtheir relatively small diameter, this is a very time consuming, laborintensive, expensive process. A weaving machine and method thatautomates the separation of the tubes is therefore needed.

SUMMARY OF THE INVENTION

The present invention relates to a weaving apparatus used to automatethe separation and spacing of the tubes of a heat exchanger so thatspacers that hold the tubes apart can be inserted between the tubes toincrease the thermal efficiency of the heat exchanger. The weavingapparatus includes a weaving mechanism having an alignment plate toalign the tubes and separation plates to separate the tubes after theyhave been aligned. During operation, the heat exchange tubes to beseparated are inserted into the weaving mechanism. The alignment platethen acts to align the tubes. Once aligned, the tubes are separated bythe separation plates so that an operator can readily insert the spacerbetween the tubes to hold them apart. The present invention thereforeeliminates the aforementioned step of separating the tubes manually thussignificantly reducing the labor, time and cost required to insertspacers between the tubes of the heat exchanger.

DESCRIPTION OF THE DRAWINGS

The invention may best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1A front perspective view of the weaving apparatus of the presentinvention.

FIG. 1B is a back perspective view of the weaving apparatus of thepresent invention.

FIG. 2 is a front view of an alignment plate used in the weavingapparatus of the present invention.

FIG. 3 is a front view of a first separator plate used in the weavingapparatus of the present invention.

FIG. 4 is a front view of a second separator plate used in the weavingis apparatus of the present invention.

FIG. 5 is an exploded perspective view of the alignment plate aligningthe tubes of the heat exchanger in the weaving apparatus.

FIG. 6 is an exploded perspective view of the first separator plate andthe second separator plate separating the tubes of the heat exchanger inthe weaving apparatus of the present invention.

FIG. 7 is a spacer used to hold the tubes of the heat exchanger apartafter the tubes are separated by the weaving apparatus of the presentinvention.

FIG. 8 is a front view of several spacers that can be used to hold thetubes of the heat exchanger apart after the tubes are separated by theweaving apparatus of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Referring to FIG. 1, the weaving apparatus 10 performing a weavingoperation on the tubes 14 of a heat exchange unit 16 is shown. Theweaving apparatus 10 includes a frame assembly 20 including a top crossmember 22, a bottom cross member 24, a first side member 26 and secondside member 28. The first side member 26 includes a first supportstructure 30, a first base structure 32, and a first guide mechanism 34.The second side member 28 includes a second support structure 36, asecond base structure 38, and a second guide mechanism 40. A first tubeseparator plate 42 and a second tube separator plate 44 are providedwithin the frame assembly 20. The guide mechanisms 34 and 40, which arepositioned on opposite sides of the frame assembly, are used to maintainthe first separator plate 42 and the second separator plate 44 withinthe frame assembly 20. An alignment plate 45 is also provided within theframe assembly 20 and within the guide mechanisms 34 and 40 (note sincethe alignment plate 45 is behind the first separator plate 42 and thesecond separator plate 44, it is only partially visible in FIG. 1A). Anactuator mechanism 46 is used to control the movement of the firstseparator plate 42, the second separator plate 44 and the alignmentplate 45 within the guide mechanisms 34 and 40. The actuator mechanism46 includes three pneumatic cylinders 48, 50, 52 and switches 54 a, 54b, 54 c mechanically coupled to the second separator plate 42, the firstseparator plate 44, and the alignment plate 45 respectively. The firstand second support structures and 36 are used to support the frameassembly 20. The first and second base structures 32 and 38 are used tobolt or otherwise fasten the weaving apparatus 10 in a stationaryposition, for example to the floor of a manufacturing or assemblyfacility. The actuator mechanism 46, under the control of switches 54 band 54 a, is configured to selectively position the first separatorplate 42 and the second separator plate 44 between tube separationpositions and reset positions within the guide mechanisms 34 and 40 ofthe frame assembly 20 respectively.

Referring to FIG. 1B, a back perspective view of the weaving apparatusof the present invention is shown. (For the sake of clarity, the weavingapparatus 10 in FIG. 1B is shown without the heat exchange unit 16.) Theback perspective view shows many of the same elements of the weavingapparatus 10 as illustrated in FIG. 1A and therefore are labeled withthe same reference numerals and will not be discussed in detail herein.The back perspective view of the weaving apparatus 10 shows a structuralcross member 59 mechanically coupled between the first and second guidemechanisms 34 and 40, brackets 62 and 64 mounted to bottom cross member24 for securing the weaving apparatus 10 to a work bench, and a plate 66which mounts the three pneumatic cylinders 48, 50, 52 to bottom crossmember 24. Also shown is the alignment plate 45 in position behind thefirst tube separator plate 42 and the second separator plate 44 withinthe frame assembly 20. The pneumatic cylinder 52 is mechanically coupledto the alignment plate 45 and is configured to selectively position thealignment plate 45 between a tube alignment position and a resetposition within the guide mechanisms 34 and 40 of the frame assembly 20.

Referring to FIG. 2, a front view of the alignment plate 45 used in theweaving apparatus of the present invention is shown. The alignment plate45 is rectangular in shape and includes a plurality of round recessregions 60 for reducing the overall weight of the plate 45 and arectangular shaped recess region 62. The top edge 64 of the recessregion 62 defines a tube alignment plane that includes a plurality ofcircular or V-shaped alignment notches 66 configured to receive theindividual tubes 14 of the heat exchanger 16 respectively. (Note thealignment notches 66 as illustrated are shown in larger proportionrelative to the other features of the alignment plate 45 for the sake ofillustration) In one embodiment, the number of alignment notches 66matches or exceeds the number of tubes 14 of the heat exchanger 16inserted into the weaving apparatus 10 and the size of the notches 66are sufficiently large to accommodate the diameter of the tubes 14. Invarious embodiments of the invention, the alignment plate 45 has a widthranging from 48 inches to 60 inches, a height ranging from 12 inches to24 inches, and the top edge 64 includes anywhere from 200 to 400alignment notches 66 each having a radius in the range of 0.63 to 0.5inches. A paddle-like member 45 a extending from the bottom of thealignment plate 45 is used to mechanically couple the alignment plate 45to the pneumatic cylinder 52 as best illustrated in FIG. 1A. Aspreviously noted, the pneumatic cylinder 52 under the control of switch54 c causes the alignment plate 45, and consequently the alignmentnotches 66, to move down to an alignment position and up to a resetposition within the guide mechanisms 34 and 40 of the frame assembly 20.

Referring to FIG. 3, a front view of the first separator plate 42 usedin the weaving apparatus 10 of the present invention is shown. The firstseparator plate 42 is rectangular in shape and includes a plurality ofround recess regions 80 for reducing the weight of the plate and arectangular shaped recess region 82. The top edge 84 of the recessedregion 82 includes a series of downwardly protruding tube separatingmembers 86. Each of the tube separating members 86 includes a set of Nreceptacles 88 a-88 n each configured to receive a heat exchanger tube.In the embodiment shown in FIG. 3, the number of receptacles 88 is four(N=4). The receptacles 88 are organized in a staggered pattern on eachof the separating members 86. In various embodiments of the invention,the top plate 42 has a width ranging from 48 inches to 60 inches, aheight ranging from 12 inches to 24 inches, and the top edge 84 includesanywhere from 50 to 100 tube separating members 86 and 2 to 8receptacles 88 per tube separating member 86. A paddle-like member 42 aextending from the alignment plate 42 is used to mechanically couple theseparator plate 42 to the pneumatic cylinder 50 as best illustrated inFIG. 1A. The pneumatic cylinder 50 under control of switch 54 b, movesthe first separator plate 42 downward to the tube separating position sothat the receptacles 88 of the tube separating members 86 can engage thetubes 14 of a heat exchanger or upward within the guide mechanisms 34and 40 of the frame assembly 20 to the reset position.

Referring to FIG. 4, a front view of the second separator plate 44 usedin the weaving apparatus 10 of the present invention is shown. Thesecond separator plate 44 is rectangular in shape and includes aplurality of round recess regions 90 for reducing the weight of theplate and a rectangular shaped recess region 92. The bottom edge 94 ofthe recessed region 92 includes a plurality of upwardly protruding tubeseparating members 96. Each of the tube separating members 96 includes aset of N receptacles 98 a-98 n. In the Embodiment shown in FIG. 4, thereceptacles 98 on each of the separating members 96 are organized in asecond staggered pattern that is the complement of the first staggeredpattern of receptacles 88 on the tube separating members 86 of the firstseparator plate 42. In various embodiments of the invention, the secondseparator plate 44 has a width ranging from 48 to 60 inches and heightranging from 12 to 24 inches, the bottom edge 94 includes anywhere from50 to 100 tube separating members 96 and 2 to 8 receptacles 98 per tubeseparating member 96. A paddle-like member 44 aextending from the secondseparator plate is mechanically coupled to the pneumatic cylinder 48 asbest illustrated in FIG. 1A. As previously noted, the pneumatic cylinder48 causes the second separator plate 44, and consequently thereceptacles 98 of the tube separating members 96 to be positioned upwardin a the tube separating position or downward in a reset position withinthe guide mechanisms 34 and 40 of the frame assembly 20.

Referring to FIG. 5, an exploded perspective view of the alignment plate45, the first separator plate 42 and the second separator plate 44 isshown prior to a weaving operation. In preparation of the weavingoperation, the switches 54 b and 54 aare activated by the operator toplace the first separator plate 42 and the second separator plate 44 intheir reset positions respectively. Specifically, the first separatorplate 42 is raised and the second separator plate 44 is lowered withinthe guide mechanisms 34 and 40 of the frame assembly 20. The tubes 14 ofa heat exchanger are then inserted through the recess regions 62, 82, 92of the three plates 45, 42, and 44 respectively. For the sake ofsimplicity, only four of the tubes 14 of the heat exchanger are shown.Next the operator lowers the alignment plate 45 from its reset positioninto the alignment position so that the alignment notches 66 of thealignment edge 64 engage the tubes 14 of the heat exchange unit. Ifnecessary, the operator may be required to move the tubes 14 so thatthey are inserted into the alignment notches 66. Once these steps arecompleted, the weaving apparatus 10 is ready to perform a weavingoperation.

Referring to FIG. 6, an exploded perspective view of the first separatorplate 42 and the second separator plate 44 after a weaving operation isshown. To begin a weaving operation, the operator is required to lowerthe first separator plate 42 into the tube separating position byactivating switch 54 b. When the first separator plate 42 is in the tubeseparating position, the lowest most receptacles 88 a of each of thetube separating members 86 engages a tube 14 positioned within thecorresponding alignment notches 66 of the alignment plate 45. Thealignment plate 45 (not visible in FIG. 6) is then raised by activatingswitch 54 c to its reset position so that it does not interfere with theremainder of the weaving operation. Next the second plate 44 is raisedby the operator using switch 45 a. As the second separator plate 44moves upward within the guide mechanisms 34 and 40, the N receptacle 98of each tube separation member 96 will engage successive tubes 14 of theheat exchanger and position them within the complementary receptacles 88of the tube separation members 86 of the first separator plate 42. Forthe sake of clarity, FIG. 6 shows only twelve tubes 14 that have beenseparated. In an actual weaving operation, all of the tubes 14 of a heatexchanger are separated in a similar manner. It should be noted that inone embodiment, the tack welds between the tubes 14 are broken beforethe heat exchanger is inserted into the weaving apparatus 10. In analternative embodiment, the tack welds are kept intact and then brokenby the tube separation action of the first separator plate 42 and thesecond separator plate 44. After the separation operation is complete,the tubes 14 are arranged in N parallel planes. Each parallel plane isdefined by a corresponding pair of the receptacles 88 a-98 a through 88n-98 n of the tube separation members 86 and 96 respectively.

Referring to FIG. 7, a side view of a spacer that can be used to holdthe tubes of the heat exchanger apart after the tubes 14 are separatedby the weaving apparatus 10 is shown. The spacer 110 is an elongatedstructural member made of relatively stiff but flexible material such asplastic or metal. The spacer 110 includes a plurality of spacer members112. Each spacer member 112 includes a plurality of spacer receptacles114 a-114 n configured to receive and hold the tubes 14 of a heatexchanger 16. After the tubes 14 are separated, the operator inserts thespacer 110 within the weaving location 12 of the weaving apparatus 10and then snaps the separated tubes 14 into the spacer receptacles 114 ofthe spacer 110 respectively. The tubes 14 are thus “locked” in place andheld apart in N parallel planes by the spacer 110. Once this operationis complete, the weaving apparatus 10 is ready to perform anotherweaving operation at a second location on the tubes 14 of the heatexchanger by pulling the tubes through the weaving apparatus 10 to thesecond position or on a new heat exchanger. In one embodiment, multiplespacers are used different positions along the length of the tubes 14 ofthe heat exchanges.

Referring to FIG. 8, a number of embodiments for alternative spacers 110is shown. These spacers 120 through 128 also each include N spacerreceptacles 114 a-114 n configured to receive and secure the tubes 14 ofa heat exchanger. These spacers 120 through 128 operate and have similarmechanical properties as spacer 110, and therefore will not be describedin detail herein.

In yet another embodiment, two spacers 110 can be used to separate thetubes 14 of a heat exchanger at each weaving location. With thisembodiment, the second spacer is positioned so that its spacer members112 and receptacles 114 are diametrically opposed to those of the firstspacer 110. As such, the receptacles 114 of both spacers engage thetubes 14 of the heat exchanger 10 from opposite sides.

While the invention has been described in relationship to the to theembodiments shown and described herein, other alternatives, embodiments,and modifications will be apparent to those skilled in the art. It isintended that the specification be only exemplary, and that the truescope and spirit of the invention be indicated by the following claims.

What is claimed is:
 1. An apparatus comprising: a weaving mechanismconfigured to accept a heat exchanger comprising a plurality ofconnected parallel tubes, the weaving mechanism including: a firstseparator plate having a first set of receptacles arranged in a firststaggered pattern, the first set of receptacles configured to engage oneof the connected parallel tubes respectively; and a second separatorplate having a second set of receptacles arranged in a second staggeredpattern, the second staggered pattern arranged in the complement of thefirst staggered pattern the second set of receptacles configured toengage one of the connected parallel tubes respectively, wherein thefirst separator plate and the second separator plate act to separate theconnected tubes into a staggered arrangement.
 2. The apparatus of claim1, wherein the weaving mechanism further comprises an alignment plateconfigured to align the tubes of the heat exchanger.
 3. The apparatus ofclaim 2, wherein the alignment plate further comprises a plurality ofalignment notches configured to align tubes of a heat exchanger in apredetermined position within the weaving mechanism.
 4. The apparatus ofclaim 3, wherein the alignment notches on the alignment plate are shapedto engage tubes of a heat exchanger.
 5. The apparatus of claim 2,further comprising a frame assembly, wherein the alignment plate ismaintained within a guide mechanism within the frame assembly.
 6. Theapparatus of claim 5, wherein the alignment plate is configured toassume a first alignment position within the guide mechanism tofacilitate the alignment of tubes of a heat exchanger and a second resetposition within the guide mechanism when the alignment plate is not inposition to align tubes of a heat exchanger.
 7. The apparatus of claim6, further comprising a first actuator mechanism mechanically coupled tothe alignment plate and configured to selectively position the alignmentplate between the first alignment position and the second reset positionwithin the guide mechanism of the frame assembly.
 8. The apparatus ofclaim 7, wherein the first actuator mechanism is a first pneumaticcylinder mechanically coupled to the alignment plate and a switchconfigured to selectively activate the first pneumatic cylinder to causethe alignment plate to move to either the first alignment position orthe second reset position within the guide mechanism.
 9. The apparatusof claim 1, wherein the first set of receptacles are arranged on aplurality of tube positioning members on the first separator plate. 10.The apparatus of claim 9, wherein each of the tube positioning membersincludes a subset of the first set of receptacles.
 11. The apparatus ofclaim 10, wherein the sub-set of receptacles on each of the tubepositioning members are arranged in the first staggered pattern.
 12. Anapparatus comprising: a weaving mechanism configured to accept a heatexchanger comprising a plurality of parallel tubes and to separate thetubes of the heat exchanger simultaneously so that a spacer can beinserted between the tubes of the heat exchanger, the weaving mechanismcomprising a first separator plate with a first plurality of tubepositioning members, wherein each of the first plurality of tubepositioning members includes a first set of N receptacles eachconfigured to receive one of the tubes of the heat exchanger, the firstset of N receptacles of the first plurality of tube positioning membersarranged in a first staggered pattern; a second separator plate with asecond plurality of tube positioning members, each of the secondplurality of tube positioning members having a second set of Nreceptacles arranged in a second staggered pattern which is thecomplement of the first staggered pattern of the first separator plate,wherein the first set of N receptacles of the first plurality of tubepositioning members of the first separator plate correspond to thesecond set of N receptacles of the second plurality of tube positioningmembers of the second separator plate respectively and wherein the firstset of N receptacles of the first plurality of tube positioning membersand the second set of N receptacles of the second plurality of tubepositioning members are positioned adjacent one another in Nsubstantially parallel planes when the first separator plate and thesecond separator plate are both in a tube separation position.
 13. Theapparatus of claim 12, wherein the weaving mechanism comprises a frameassembly having a guide mechanism wherein the first separator plate issecured within the guide mechanism of the frame assembly.
 14. Theapparatus of claim 13, wherein the second separator plate is securedwithin the guide mechanism of the frame assembly.
 15. The apparatus ofclaim 14, further comprising an actuator mechanism mechanically coupledto the first plate and the second separator plate and configured toselectively position the first separator plate and the second separatorplate in either the tube separation position or a reset position withinthe guide mechanism of the frame assembly.
 16. The apparatus of claim15, wherein the actuator mechanism comprises a first pneumatic cylindermechanically coupled to the first separator plate and a first switchconfigured to selectively activate the first pneumatic cylinder toposition the first separator plate to either the tube separationposition or the reset position within the guide mechanism of the frameassembly.
 17. The apparatus of claim 15, wherein the actuator mechanismcomprises a second pneumatic cylinder mechanically coupled to the secondseparator plate and a second switch configured to selectively activatethe second pneumatic cylinder to position the second separator plate toeither the tube separation position or the reset position within theguide mechanism of the frame assembly.
 18. The apparatus of claim 10,wherein the receptacles on the fist separator plate are shaped toengaged the tubes of a heat exchanger.